1. Technical Field
The presently disclosed subject matter relates to a structure of a vehicular lamp having a light source including a plurality of light emitting diodes (LEDs).
2. Description of the Related Art
A vehicular lamp 90 of the related/conventional art may include a light source 91 and a flat mirror 92 located in a direction that is forward and in the illumination direction of the light source 91, as shown in FIG. 3. The light source 91 is composed of a halogen bulb 91a and a paraboloid of revolution 91b to generate a paralleled light. The light source 91 is attached in a housing 93 to emit light upward.
In the housing 93, the flat mirror 92 is arranged basically at an angle of 45° with respect to the light from the light source 91 such that it can reflect the light from the light source 91 into a horizontal direction. The reflected light is then externally projected as a horizontal light through a lens 96 arranged in a corresponding side 95 of the housing 93.
In the case of a truck or the like, when an increase in load on a carrier lifts or angles the front of the vehicle upward as a whole, the light from the vehicular lamp 90 also is caused to be directed upward, and possibly dazzles oncoming cars. Accordingly, for example, the amount of gravity-caused distortion of suspension springs is used to measure the pitch angle of the body. In this case, actuators 97 may be employed to adjust the angle of elevation of the flat mirror 92 so as to correct the amount of distortion to always keep the illumination direction horizontal (See for example, U.S. Pat. No. 4,363,085, the entire disclosure of which is incorporated herein by reference).
In recent years, there is an increasing trend towards the utilization of LEDs in the light source of vehicular lamps. Compared to an incandescent bulb and a halogen bulb, an LED has a smaller amount of light per element. This point requires the use of more LEDs, and results in a problem associated with heat radiation in the housing and a problem associated with the development of an attaching method that achieves a correct illumination direction.